Wow. That didn't look really bad. I actually liked it. Just two things I think you should know however.
1. The area around all the stuff (you know, the utter blankness.) Could use a few hills.
2. When I left the playing field I ran off the edge. You might want to put a invisible barrier or something over there.

Also, there A LOT OF CAVERNS UNDERGROUND! There's also at the very very buttom, lava. There could be random height of other lava though. There's also water that goes rapidly down and sideways, but not up. Lava can't go up either. There's also other elements, like brick, glass, TNT, and library shelf's.

As you can see, this looks terrible. Each block is 48x48x48 so I thought it would work, but in reality all it did was lower the quality of the shadows. It will not make shadows per-block like I was expecting. Also, minecraft shadows are straight down, they never extend across other blocks :3

I was trying to render a map with a lightscale of 4, so the shadows would be super high quality but vrad,-the process of hammer that renders shadows- crashed.